On day 6 we got a chance to come back to Jameo de la Puerta Falsa to recover more data and scans of the lava tube, as well as to do some scouting for possible sites and fly more kites. As I brought a wide variety of kites and the wind was favorable that day, I was able to characterize the remainder of the kites in different sites (puffer, lifter, and cell kite). 

This session proved to be very productive as we got plenty of data from the lava tubes and our sites and I was able to successfully fly a 3d camera with a puffer kite –not an easy task as the rig that we were planning on using did not work very well because of the weight of the camera. 

While flying the puffer kite I encountered an amazing sonic phenomenon: the line of the kite, when in tension and encountering a constant flow of wind in a certain speed, acts as a large-scale vibratory instrument that resonates all the way to the handle of the kite, creating a giant aeolian harp. 

This sonic phenomenon is known to be caused by the Karman Vortex Street effect. It makes sense that, wind being a fluid and the string a tubular obstacle, on specific circumstances of constant flow of wind and tension of the string we get a beautiful whistling sound that gives us a live sonic reference of the strength and behavior of the wind. 

Something that fascinates me about this phenomenon is that it is not dependent on scale, Karman Vortex Street effect can happen in a micro scale but also on a macro scale, it can happen to the string of our kite but also in an atmospheric scale. This reminded me of the depictions of the phenomenon in simulators but also the famous images from NASA demonstrating this effect in a planetary scale, one of these is usually using collections of islands or archipelagos as examples. I went then to check live satellite imagery only to confirm that we were experiencing a Karman Vortex Street effect on an atmospheric scale ourselves. 

This was a beautiful realization, a moment when a phenomenon was present in two different scales and experienced in the same site. Kites can act as probes into the atmosphere and become carriers and instruments by themselves, demonstrating how these invisible fluids move and connect us across scales. 

References:

-       Von Kármán, T. (1954). Aerodynamics: selected topics in the light of their historical development. Cornell University Press. (Page 68)

-       Kircher, A. (1966). Phonurgia nova. Broude Brothers.

-       Source: Zoom Earth, images from Geostationary Operational Environmental Satellite (GOES), NOAA/NESDIS/STAR, GOES-East. https://zoom.earth/maps/satellite/#view=25.34,-20.196,6.54z/date=2024-02-16,11:10,-5